1. Field of the Invention
The present invention generally relates to optical disk apparatuses and, more particularly, to an optical disk apparatus, which records/reproduces information on/from an optical disk by irradiating a laser beam onto the optical disk, and has a drawer detection switch for detecting a state of a drawer having a placement part on which the optical disk is placed.
2. Description of the Related Art
Generally, an optical disk apparatus comprises: a cabinet accommodating a circuit board on which control circuits providing various functions necessary for the apparatus are mounted; and a drawer slidable within the cabinet between a loaded position and an unloaded position and having an optical pickup and a placement part on which an optical disk is placed. A semiconductor laser (a laser diode: LD) is used as an illuminant provided in an optical pickup. In order to protect a user from being exposed to a laser beam, the semiconductor laser is controlled by a controlling means so that the semiconductor laser is turned off when the drawer is at the unloaded position.
However, if some troubles arise in the control means for controlling on/off of the semiconductor laser, the semiconductor laser may emit a laser beam even when the drawer is out of the apparatus, that is, the drawer is at the unloaded position with respect to the cabinet. In such a case, it is possible that a laser beam unnecessarily emitted by the semiconductor laser enters user's eyes and the user becomes blind in the worst case.
In order to eliminate such a problem, Japanese Laid-Open Patent Application No. 5-135397 discloses an optical disk apparatus, which aims to protect a user from a laser beam. The optical disc apparatus disclosed in this patent document uses a detection switch for detecting existence of a cartridge accommodating an optical disk and an electronic circuit for maintaining safety. The optical disk apparatus may use a plurality of detection switches to improve safety.
However, using the special electronic circuit for improving safety as mentioned above leads to an increase in the cost of the optical disc apparatus. Moreover, using a plurality of detection switches to detect a state of the drawer leads to occupancy of a limited mounting area in the circuit board.